I use the painters tape to mark a straight line and then go from corner to corner and move outward from there. I have not had any trouble going the full length of the quilt.
Pretty much the same as Tiffany.

I start in a corner for diagonal lines and I use an old pizza cutter and a ruler to mark my lines. I am lazy and hate to remove the painters tape. I was using a Hera marker and it kind of drags on a long line I thought that it would be nice if it rolled like my chalk marker (which is more or less worn out)Then the lightbulb went on. My pizza cutter is so dull it would not even cut pizza anymore so I tried it. I did test it first to be sure.

Today I am quilting very long diagonal lines across the log cabin quilt that I'm making for DH, using blue painter's tape, and a walking foot on my Bernina (old model 830). On a rest break now because my shoulders hurt.

I saw a picture of a "manly" quilt done completely in single direction, diagonal lines that I got my heart set on doing. Right now I'm questioning my sanity! Keeping that sucker pinned and rolled up on the bias is a challenge, as is stitching. There are no landmarks to keep the lines straight.

I'm quilting every inch, so I found that if I use 1 inch painter's tape every other line, it is adequate. The alternate times I use the measuring guide on the walking foot set for one inch.

Cross my fingers, no pleats on the back yet, but I do have some wobbles in my lines from shoving the bulk of the quilt around.

Dull pizza cuter!!! What a great idea!!!

Ditto here!

You could submit that tip to Fons and Porter's and I bet that you would win a subscription to their magazine! What a great tip! Thanks for sharing your "light bulb" moment!

After I stitch from corner to corner, I start the next row from the opposite side of where I started the first row. I continue alternating rows. If this doesn't make sense, I'll try to explain in a different way.

Connie - Indy